Solid reactor core fuel assembly and shielding system

Abstract

The invention discloses a solid-state reactor core fuel assembly and a shielding system and belongs to the field of nuclear power. The solid reactor core fuel assembly comprises a base body with a fuel rod mounting hole, a fuel rod is arranged in the fuel rod mounting hole in a penetrating manner, a sealing section is formed between the fuel rod mounting hole and the end part of the fuel rod mounting hole, a deep hole end plug is arranged in the sealing section to seal the fuel rod in the fuel rod mounting hole, and end cover plates are fixed at two ends of the base body. According to the solid reactor core fuel assembly, multi-layer containing can be formed on reactor core radioactive substances, and the radioactive substances are sealed in the fuel rod mounting holes of the base body through the deep hole end plugs under the condition that a fuel rod cladding is damaged, so that the safety and reliability of a solid reactor core are improved. The invention also provides a solid reactor core shielding system.

Description

Technical Field

[0001] The invention belongs to the field of nuclear power, and in particular relates to a solid core fuel assembly and a shielding system. Background Art

[0002] As a new type of reactor, the solid core does not use the liquid primary circuit of the pressurized water reactor, but uses solid media to conduct heat generated by the fuel rods. Due to the omission of the high-pressure primary circuit, the solid core has the advantages of simple structure, small size, and good inherent safety. However, the solid core also lacks the safety barrier of the pressure boundary of the pressurized water reactor coolant system. Once the fuel rod is damaged, the risk of leakage is also increased accordingly.

[0003] Therefore, providing a solid core fuel assembly with higher safety has positive significance for further improving the safety and reliability of the solid core. Summary of the invention

[0004] The purpose of the present invention is to provide a solid core fuel assembly to improve the safety and reliability of the solid core. The present invention also provides a solid core shielding system.

[0005] According to an embodiment of one aspect of the present invention, a solid core fuel assembly is provided, the fuel assembly comprising a fuel rod and a matrix, the matrix being provided with a fuel rod mounting hole, the fuel rod being inserted into the fuel rod mounting hole of the matrix. The fuel assembly also comprises a deep hole end plug and an end cover plate; wherein,

[0006] Sealing sections are respectively provided between the two ends of the fuel rod and the end of the fuel rod mounting hole;

[0007] The deep hole end plug is installed and fixed in the sealing section to seal the fuel rod in the fuel rod installation hole;

[0008] The end cover plates are fixed at two ends of the base.

[0009] By providing deep hole end plugs, the fuel rods can be sealed in the matrix to prevent radioactive materials from leaking out of the solid core matrix when the fuel rod cladding is damaged, thereby improving the safety of the solid core.

[0010] Furthermore, in some embodiments, a groove is provided on the outer circumference of the deep hole end plug, and a sealing ring is provided in the groove.

[0011] The sealing ring can improve the sealing performance of the deep hole end plug, wherein the sealing ring can be made of high temperature resistant alloy material or composite material.

[0012] Furthermore, in some embodiments, a sealant is provided on the outer peripheral side of the deep hole end plug.

[0013] The sealant can further improve the sealing performance of the deep hole end plug and make the installation of the deep hole end plug more secure.

[0014] Furthermore, in some embodiments, the end cover is provided with a mounting tube matching the fuel rod mounting hole, the mounting tube is inserted into the sealing section, and the deep hole end plug is installed and fixed in the mounting tube.

[0015] Furthermore, in some embodiments, the deep hole end plug is fixed by welding.

[0016] Furthermore, in some embodiments, the inner wall surface of the sealing section of the fuel rod mounting hole and the outer peripheral side of the deep hole end plug are provided with matching threads, and the deep hole end plug is fixed to the sealing section by threaded connection.

[0017] Furthermore, in some embodiments, a gap is reserved between the deep hole end plug and the end surface of the fuel rod.

[0018] Furthermore, in some embodiments, the gap between the fuel rod with high burnup and the deep hole end plug is larger than the gap between the fuel rod with low burnup and the deep hole end plug.

[0019] Furthermore, in some embodiments, the deep hole end plug is made of one or more combinations of nickel-based alloys, stainless steel, zirconium alloys, and SiC composite materials.

[0020] According to another aspect of the present invention, there is provided a solid core shielding system, which includes a fuel assembly and a solid core containment vessel, wherein the fuel assembly adopts the solid core fuel assembly provided in any of the aforementioned embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 This is a schematic diagram of the structure of a solid core fuel assembly in one embodiment;

[0022] Figure 2 An exploded view of a solid core fuel assembly in one embodiment;

[0023] Figure 3 This is a schematic diagram of a deep hole end plug structure in one embodiment;

[0024] Figure 4 A schematic diagram of a deep hole end plug structure in another embodiment;

[0025] Figure 5 for Figure 4 Schematic diagram of the assembly of the medium and deep hole end plug;

[0026] Figure 6 It is a schematic diagram of the assembly of the deep hole end plug and the end cover in another embodiment.

[0027] Meaning of the reference symbols:

[0028] 1-end cover plate; 2-deep hole end plug; 3-base; 4-fuel rod mounting hole; 5-thread; 6-sealing ring; 7-mounting tube; 8-slot.

[0029] The purpose of the above drawings is to explain the present invention in detail so that those skilled in the art can understand the technical concept of the present invention, but it is not intended to limit the present invention. For the sake of simplicity, the above drawings only schematically illustrate the structures related to the technical features of the present invention, and do not strictly follow the actual proportions to draw the complete structure and all details. DETAILED DESCRIPTION

[0030] The present invention is further described in detail below through specific embodiments in conjunction with the accompanying drawings.

[0031] Reference to "embodiments" herein means that a particular feature, structure, or characteristic described in conjunction with the embodiments may be included in at least one embodiment of the present invention. The phrase appearing in various locations in the specification does not necessarily refer to the same embodiment, nor is it limited to mutually exclusive independent or alternative embodiments. Those skilled in the art should be able to understand that the embodiments herein may be combined with other embodiments without causing structural conflicts.

[0032] In the description of this article, unless otherwise clearly specified and limited, the technical terms "installed", "connected", "connected" and the like should be understood in a broad sense, for example, it can be a movable connection, a fixed connection or an integral connection. For ordinary technicians in this field, the specific meanings of the above terms in the embodiments of this application can be understood according to specific circumstances.

[0033] In the description of this document, terms indicating orientation or positional relationships, such as "up", "down", "left", "right", "horizontal", "vertical", "height", "length", and "width", are intended to accurately describe the embodiments and simplify the description, but are not intended to limit the parts or structures involved to have a specific orientation, be installed or operate in a specific orientation, and should not be construed as a limitation on the embodiments in this document.

[0034] In the description of this article, the terms "first", "second" and the like are only used to distinguish different objects, and cannot be understood as indicating relative importance or limiting the quantity, specific order or primary and secondary relationship of the described technical features. In the description of this article, the meaning of "plurality" is at least two.

[0035] The solid core is a nuclear reactor that uses the fuel assembly matrix as a heat transfer medium and cooperates with the characteristics of the heat transfer equipment to complete the heat release of the nuclear fuel. This solid core structure is quite different from the traditional pressurized water reactor or gas-cooled reactor. It eliminates the complex flow channel for the flowing cooling medium, does not require a coolant loop and a main pump, and has no risk of loss of flow. It has technical characteristics such as inherent safety, silent operation, reliable simplification, etc.

[0036] Due to the omission of the flowing cooling medium and the complex primary circuit, the all-solid-state core lacks the pressure boundary safety barrier of the pressurized water reactor coolant system, which increases the probability and risk of radioactive material leakage into the environment and does not meet the design requirements of the safety barrier in nuclear power regulations. Therefore, an embodiment of the present invention provides a solid-state core fuel assembly design with a multi-layer safety barrier to meet the requirements of nuclear power regulations and reduce the risk of radioactive material leakage, thereby improving the safety of the solid-state core.

[0037] In one aspect of the present invention, a solid core fuel assembly is provided. The structure of the fuel assembly is as follows: Figure 1 and Figure 2 As shown, it includes fuel rods (not shown) and a matrix 3, on which a plurality of fuel rod mounting holes 4 are provided, and the fuel rods are inserted into these fuel rod mounting holes 4. In the array formed by the arrangement of the fuel rods, heat pipes are inserted at intervals to conduct the heat generated in the fuel rods. A plurality of such fuel assemblies are stacked together to form a solid heat transfer structure of a solid core, and are closed by a containment shell arranged on the outside.

[0038] The axial length of the fuel rod is shorter than the axial length of the fuel rod mounting hole 4. When the fuel rod is inserted into the fuel rod mounting hole 4, a distance is reserved between its two ends and the end of the fuel rod mounting hole 4 as a sealing section. Deep hole end plugs 2 are respectively installed and fixed in the sealing sections at both ends of the fuel rod mounting hole 4. The deep hole end plugs 2 seal the fuel rod in the fuel rod mounting hole 4 and form a closed structure outside the fuel rod cladding. In this way, when the fuel rod cladding ruptures or melts due to radiation swelling, the deep hole end plugs 2 can continue to seal the radioactive substances released from the fuel rod cladding in the fuel rod mounting hole, thereby achieving the effect of improving the safety of the solid-state core.

[0039] End cover plates 1 are fixed at both ends of the substrate 3, and the end cover plates 1 serve as a fixing structure to fix the fuel assembly in the solid core.

[0040] In some embodiments, the end cover plate 1 itself has a sealing function and can seal the fuel rod installation hole 4 .

[0041] In some embodiments, Figure 3As shown, the outer peripheral side of the deep hole end plug 2 is provided with a thread 5, and the sealing section of the fuel rod mounting hole 4 is correspondingly provided with a thread structure matching the thread 5, so that the deep hole end plug 2 can be fixedly installed in the sealing section of the fuel rod mounting hole 4 through the thread 5.

[0042] In a further preferred embodiment, sealant may be provided on the thread 5 so that the deep hole end plug 2 is installed more firmly in the sealing section of the fuel rod installation hole 4 .

[0043] In a preferred embodiment, a groove 8 is provided on a surface of the deep hole end plug 2 facing the outer side of the base body 3 so that the deep hole end plug can be screwed into the sealing section of the fuel rod mounting hole 4 by using an assembly tool.

[0044] In a preferred embodiment, if Figure 4 As shown, the outer peripheral side of the deep hole end plug 2 is provided with a groove, and a sealing ring 6 is provided in the groove. Figure 5 As shown, the sealing ring 6 can be squeezed and deformed to seal the circumferential gap between the deep hole end plug 2 and the fuel rod mounting hole 4.

[0045] The deep hole end plug 2 provided with a sealing ring 6 can be clamped in the fuel rod mounting hole 4, or can be fixedly connected to the inner wall of the fuel rod mounting hole 4 by welding. A supporting structure extending into the fuel rod mounting hole 4, such as a supporting rod or a supporting tube, can also be provided on the end cover plate 1 to tighten the deep hole end plug 2 in the axial direction.

[0046] In other embodiments, Figure 6 As shown, the end cover plate 1 is provided with a mounting tube 7, and the position of the mounting tube 7 corresponds to each fuel rod mounting hole 4. When the end cover plate 1 is installed at both ends of the substrate 3, the mounting tube 7 is inserted into the sealing section of the fuel rod mounting hole 4, and the outer wall of the mounting tube 7 and the inner wall of the fuel rod mounting hole 4 form an interference fit to form a seal. The deep hole end plug 2 is installed and fixed in the mounting tube 7 to achieve the sealing of the fuel rod mounting hole 4.

[0047] In a further preferred embodiment, the deep hole end plug 2 can be welded and fixed to the inner wall of the mounting tube 7. The deep hole end plug 2 can be welded and fixed to the mounting tube 7 in advance before the fuel assembly is assembled to save assembly time on site; or it can be welded and installed one by one during the overall assembly of the fuel assembly.

[0048] In a preferred embodiment, a gap is reserved between the deep hole end plug 2 and the end of the fuel rod to accommodate the fission gas generated by the fuel rod burnup and to accommodate the axial thermal deformation and irradiation growth of the entire fuel rod.

[0049] In a further preferred embodiment, according to the distribution of the fuel rods in the entire solid-state core, the fuel rods at different positions have different burnup depths. For the high-burnup fuel rods, the gap reserved between their ends and the deep hole end plug 2 is larger than the gap reserved between the low-burnup fuel rods and the deep hole end plug 2, so as to avoid excessive fission gas pressure generated by the high-burnup fuel rods in the later stage.

[0050] In a preferred embodiment, the deep hole end plug 2 can be made of alloy materials such as heat-resistant nickel-based alloys, zirconium alloys, stainless steel, etc., can also be made of composite materials with good tolerance to neutron irradiation such as SiC composite materials, and can also be made of a combination of multiple of the above materials. For example, the main body of the deep hole end plug 2 is made of SiC composite materials, and the outer peripheral side is provided with an outer side wall made of metal material for easy welding and fixing.

[0051] The solid core of the solid core fuel assembly provided by the above embodiment has a three-layer composite shielding system from the inside to the outside. Among them, the fuel rod cladding forms a containment for the fuel core block, which serves as the first layer of safety shielding structure; the deep hole end plug 2 seals the fuel rod in the fuel rod installation hole 4 of the substrate 3 to prevent the leakage of radioactive materials after the fuel rod cladding is damaged, forming the second layer of safety shielding structure; the solid core containment shell seals all the fuel assemblies inside, isolates the fuel assemblies from the external environment, and forms the third layer of safety shielding structure.

[0052] The solid-state core safety shielding system can form multi-layer shielding for the active area within the solid-state core, more effectively maintain the long-term containment of radioactive materials in the core under accident conditions, and improve the safety and reliability of the solid-state core.

[0053] The purpose of the above embodiments is to further explain the present invention in detail in conjunction with the accompanying drawings so that those skilled in the art can understand the technical concept of the present invention. Within the scope of the present invention, the optimization or equivalent replacement of the part structure involved, and the combination of the implementation methods in different embodiments without conflict of structure and principle, all fall within the protection scope of the present invention.

Claims

1. A solid core fuel assembly, comprising a fuel rod and a substrate, wherein the substrate is provided with a fuel rod mounting hole, and the fuel rod is inserted into the fuel rod mounting hole of the substrate, characterized in that: It also includes a deep hole end plug and an end cover plate; wherein, Sealing sections are respectively provided between the two ends of the fuel rod and the end of the fuel rod mounting hole; The deep hole end plug is installed and fixed in the sealing section to seal the fuel rod in the fuel rod installation hole; The end cover plates are fixed at two ends of the base.

2. The solid core fuel assembly according to claim 1, characterized in that: A groove is arranged on the outer peripheral side of the deep hole end plug, and a sealing ring is arranged in the groove.

3. The solid core fuel assembly according to claim 1, characterized in that: The outer peripheral side of the deep hole end plug is provided with sealant.

4. The solid core fuel assembly according to claim 1, characterized in that: The end cover is provided with a mounting tube matching the fuel rod mounting hole, the mounting tube is inserted into the sealing section, and the deep hole end plug is installed and fixed in the mounting tube.

5. The solid core fuel assembly according to any one of claims 1 to 4, characterized in that: The deep hole end plug is fixed by welding.

6. The solid core fuel assembly according to any one of claims 1 to 3, characterized in that: The inner wall surface of the sealing section of the fuel rod installation hole and the outer peripheral side of the deep hole end plug are provided with matching threads, and the deep hole end plug is fixed to the sealing section through threaded connection.

7. The solid core fuel assembly according to any one of claims 1 to 4, characterized in that: A gap is reserved between the deep hole end plug and the end surface of the fuel rod.

8. The solid core fuel assembly according to claim 7, characterized in that: The gap between the fuel rod with high burnup and the deep hole end plug is larger than the gap between the fuel rod with low burnup and the deep hole end plug.

9. The solid core fuel assembly according to any one of claims 1 to 4, characterized in that: The deep hole end plug is made of a combination of one or more of nickel-based alloy, stainless steel, zirconium alloy and SiC composite material.

10. A solid core shielding system, characterized in that: include Fuel assemblies and solid core containment, of which: The fuel assembly adopts the solid core fuel assembly as described in any one of claims 1 to 9.

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